The way to turn off your iPhone has changed with recent generations, including the 12. These techniques also work on the iPhone X range and 11 too.
Turn Off an iPhone 12
- Hold down the volume up or down button and the button on the right-hand side at the same time.
- Hold and slide ‘slide to power off’ option After 30 seconds your device will be shut down.
To turn on an iPhone 12, hold down the button on the right-hand side until the Apple logo appears (it will take a few seconds).